Local Search in Physical Distribution Management

摘要

Physical distribution management presents a variety of decision making problemsat the three levels of strategic, tactical and operational planning. Decisions relating to the location of facilities (plants, warehouses or depots) may be viewed as strategic, while problems of fleet size and fleet mix determination can be termed tactical. On the operational level, two problems prevail: the routing of capacitated vehicles through a collection of customers to pickup or deliver goods, and the scheduling of vehicles to meet time or precedence constraints imposed upon their routes. The importance of effective and efficient distribution management is evident from its associated costs. Physical distribution management at the operational level, which is considered in this paper, is responsible for an important fraction of the total distribution costs. Not surprisingly, there is a growing demand for planning systems that produce economical routes. Some of the resulting vehicle routing and scheduling models will be discussed in this paper. The first is the vehicle routing problem with time windows. The second model is the pickup and delivery problem with time windows. The paper is organized as follows. Section 2 presents a survey of the various methods that have been proposed to implement k-exchange methods for constrained variants of the traveling salesman problem.